Answer: You are correct. The answer is choice C) Law of Detachment.
==========================================================
Step-by-step explanation:
The law of detachment takes this format
- Premise 1: If P, then Q
- Premise 2: statement P is true
- Conclusion: Therefore, statement Q is also true
The given argument can be rephrased as such
- Premise 1: If it rains, then I get tired
- Premise 2: It's raining today
- Conclusion: I'm going to take a nap (i.e. I got tired)
The fact that premise 2 is true then leads to a chain events of the back half of premise 1 being true. You can think of it like a set of dominoes in a way.